26,005 research outputs found

    Designing Illumination Lenses and Mirrors by the Numerical Solution of Monge-Amp\`ere Equations

    Full text link
    We consider the inverse refractor and the inverse reflector problem. The task is to design a free-form lens or a free-form mirror that, when illuminated by a point light source, produces a given illumination pattern on a target. Both problems can be modeled by strongly nonlinear second-order partial differential equations of Monge-Amp\`ere type. In [Math. Models Methods Appl. Sci. 25 (2015), pp. 803--837, DOI: 10.1142/S0218202515500190] the authors have proposed a B-spline collocation method which has been applied to the inverse reflector problem. Now this approach is extended to the inverse refractor problem. We explain in depth the collocation method and how to handle boundary conditions and constraints. The paper concludes with numerical results of refracting and reflecting optical surfaces and their verification via ray tracing.Comment: 16 pages, 6 figures, 2 tables; Keywords: Inverse refractor problem, inverse reflector problem, elliptic Monge-Amp\`ere equation, B-spline collocation method, Picard-type iteration; OCIS: 000.4430, 080.1753, 080.4225, 080.4228, 080.4298, 100.3190. Minor revision: two typos have been corrected and copyright note has been adde

    CAPTURING THE USE OF COLLOCATION IN ARGUMENTATIVE ESSAY WRITING ON SECOND SEMESTER STUDENTS IN ENGLISH EDUCATION DEPARTMENT OF IAIN SURAKARTA

    Get PDF
    ABSTRACT Amalia Faulien. 2017. Capuring the Use of Colocation in Argumentative Essay Writing on Second Semester Students in English Education Department of IAIN Surakarta. Thesis. English Education Department. Islamic Education and Teacher Training Faculty. State Islamic Institute of Surakarta. Advisor : Dr. Imroatus Solikhah, M. Pd. Key words : Collocation, lexical collocation, grammatical collocation, Argumentative Essay Collocation is a combination of words in a language that happens very often and more frequently than would happen by chance. The aim of this study is to analyze the types of collocation used by 2nd semester students and the incorrect collocation made by the students in their argumentative essay writing. The researcher used content analysis with descriptive qualitative approach. The data was collected by documenting the types and incorrect collocation on the students‟ worksheet of argumentative essay writing. The data were analyzes by reducing the data, presenting the data, analyzing the data by using Benson theory and taking the conclusion and verification. This research used source triangulation and verification based on Oxford Collocation Dictionary to get an appropriate data. There are two findings of this research. First, the types of collocation used by the students. Second, the incorrect collocation made by the students. The result of the study showed that there are 9 types pattern consist of lexical and grammatical collocation. The total of collocation used by the students in their argumentative essay are 127 collocation, it also showed that most of collocation produced by the students is lexical collocation there are 74 collocation, while grammatical collocation are accounted 58 collocation. Adjective + Noun is the pattern of lexical collocation types which commonly occurred in students argumentative essay. The second finding is the incorrect collocations made by the students there are: 1) quality character, 2) social domain, 3) far distance, 4) attractive dressed, 5) important energy, 6) we must pause, 7) to understand the problem, 8) the likelihood of blindness, 9) don‟t wear, 10) education ladder, 11) pretty easy, 12) rectify our mindset, 13) quality generation, 14) observe intently, 15) the goal of doing homework, 16) to managed, 17) tremendous pain and 18) virtual world. From those findings, there are many types of collocation used by 2nd semester students and the incorrect collocation is still low. Based on those findings, the researcher has suggestion for other researcher to investigate the relationship between student‟s collocation competence and their academic success. It will be of great value to understand whether collocation knowledge helps students increase their academic achievement

    COLLOCATION OF ENGLISH, ARABIC, AND INDONESIAN COVID-19 TERMS

    Get PDF
    This paper studies language and translation of the term related to Covid-19. The background of this research is many new vocabularies related to Covid-19 is borrowing term. This study attempts to find answers to the following question: a) What kind of collocations are related to the term Covid-19 pandemic in English, Arabic, and Indonesian? b) How is the pattern of word order forming collocations with the term Covid-19 pandemic in English, Arabic, and Indonesian? This study addressed the emergence of new English, Arabic, Indonesian collocation related to Covid-19 using H. Men’s collocation theory. This study used newspapers, namely Republika, BBC, al-Jazeera online that show Covid-19 as the standard procedure for collecting data. This study used corpus linguistic to analyze collocation, concordance, and syntax analysis, models. The Covid-19 domain has chosen because the Indonesian term in this domain uses a lot of loanwords. The source of the data was a basic-words and compound term. The investigation informed several aspects of findings, such as identifying the pattern of collocation, borrowing, and collocation term of coronavirus concept

    The Organization of Words in Mental Lexicon: Evidence From Word Association Test

    Full text link
    Both in psychology and linguistics studies, memory is one of the core of interests amongst researchers. In linguistics, memory is the place where language processes consisting of language perception, storage, and access of words take place. Words, in memory, are stored in complex, clear, well-organized, and ordered networks called nodes, which can be represented by World Wide Web. This word organization in psycholinguistics is referred to mental lexicon. This study aims to investigate what kind of nodes representation stored in mental lexicon of foreign language learners. Word Association Test (WAT), the well-known study method in both psychology and linguistics studies, is employed by using English Swadesh word list as the stimulus to elicit the lexical relation amongst words. The basic principle of the test is giving a stimulus to respondents and asking them to give the very first word coming out of their mind. Respondents are undergraduate students of English Literature a university in Indonesia. Findings of this research support the previous findings stating that non-native speakers tend to make syntagmatic relation, which is mostly dominated by collocation association. Interestingly, the finding also shows that the words network in mental lexicon involves a dynamic development based on experience and perception of the respondents

    Towards a collocation writing assistant for learners of Spanish

    Get PDF
    This paper describes the process followed in creating a tool aimed at helping learners produce collocations in Spanish. First we present the Diccionario de colocaciones del español (DiCE), an online collocation dictionary, which represents the first stage of this process. The following section focuses on the potential user of a collocation learning tool: we examine the usability problems DiCE presents in this respect, and explore the actual learner needs through a learner corpus study of collocation errors. Next, we review how collocation production problems of English language learners can be solved using a variety of electronic tools devised for that language. Finally, taking all the above into account, we present a new tool aimed at assisting learners of Spanish in writing texts, with particular attention being paid to the use of collocations in this language

    Human sperm accumulation near surfaces: a simulation study

    Get PDF
    A hybrid boundary integral/slender body algorithm for modelling flagellar cell motility is presented. The algorithm uses the boundary element method to represent the ‘wedge-shaped’ head of the human sperm cell and a slender body theory representation of the flagellum. The head morphology is specified carefully due to its significant effect on the force and torque balance and hence movement of the free-swimming cell. The technique is used to investigate the mechanisms for the accumulation of human spermatozoa near surfaces. Sperm swimming in an infinite fluid, and near a plane boundary, with prescribed planar and three-dimensional flagellar waveforms are simulated. Both planar and ‘elliptical helicoid’ beating cells are predicted to accumulate at distances of approximately 8.5–22 μm from surfaces, for flagellar beating with angular wavenumber of 3π to 4π. Planar beating cells with wavenumber of approximately 2.4π or greater are predicted to accumulate at a finite distance, while cells with wavenumber of approximately 2π or less are predicted to escape from the surface, likely due to the breakdown of the stable swimming configuration. In the stable swimming trajectory the cell has a small angle of inclination away from the surface, no greater than approximately 0.5°. The trapping effect need not depend on specialized non-planar components of the flagellar beat but rather is a consequence of force and torque balance and the physical effect of the image systems in a no-slip plane boundary. The effect is relatively weak, so that a cell initially one body length from the surface and inclined at an angle of 4°–6° towards the surface will not be trapped but will rather be deflected from the surface. Cells performing rolling motility, where the flagellum sweeps out a ‘conical envelope’, are predicted to align with the surface provided that they approach with sufficiently steep angle. However simulation of cells swimming against a surface in such a configuration is not possible in the present framework. Simulated human sperm cells performing a planar beat with inclination between the beat plane and the plane-of-flattening of the head were not predicted to glide along surfaces, as has been observed in mouse sperm. Instead, cells initially with the head approximately 1.5–3 μm from the surface were predicted to turn away and escape. The simulation model was also used to examine rolling motility due to elliptical helicoid flagellar beating. The head was found to rotate by approximately 240° over one beat cycle and due to the time-varying torques associated with the flagellar beat was found to exhibit ‘looping’ as has been observed in cells swimming against coverslips
    • …
    corecore